Rolled sheets having openings therethrough and process for their manufacture



United States Patent ROLLED SHEETS HAVING OPENINGS THERE- THROUGH ANDPROCESS FOR THEIR MANUFACTURE Addison Y. Gunter and Thomas E. Owen,Houston, Tex., assignors to Hudson Engineering Corporation, Houston,Tex., a corporation of Texas Filed Feb. 24, 1964, Ser. No. 346,804 6Claims. (Cl. 29-61) This invention relates to the art of formingopenings through sheets of malleable material, such as malleable metalsor malleable plastics. It includes a process for forming openingsthrough such sheets and a product which has particular utility as partsof racks for receiving elongate objects, or for sides of ventilatedboxes or cabinets, but is not limited to such use.

Expanded metal has long been made by slitting a sheet of metal with theslits in staggered relationship to each other and applying tension tothe slit sheet to expand the slits into diamond shape. This process isan excellent one when diamond-shaped openings have total area equivalentto a major part of the area of the expanded sheet are desired; 'but whenopenings of other shapes, such as oval or crescent shape, are desired,and especially when the total area of the openings is to form only aminor part of the total area of the expanded sheet, this method is notsatisfactory as suflicient tension on the sheet to expand the openingsmay tear the sheet.

It is an object of this invention to provide a process for forming aseries of openings through a sheet of malleable material which iseffective to form openings of oval, substantially rectangular orcrescent shape.

Another object is to provide a process in which openings through thesheet of malleable material are shaped by application of rolling stressto the sheet.

Another object is to provide a process in which openings are torn in amalleable sheet during a rolling step and expanded to selected width.

Another object is to provide a process for shaping a series of openingsin a sheet of malleable material by expanding the openings to selectedwidth and size by application of rolling stress.

Another object is to provide a rolled sheet of malleable material havingat least one series of openings therethrough in which the openings areof substantially equal size and shape and are substantially equidistantfrom each other in series.

Other objects, advantages and features of this invention will beapparent to one skilled in the art upon a consideration of the writtenspecification, the attached claims and the annexed drawings,

The process of the present invention includes a rolling step in which asubstantial differential in rolling stress is applied to adjacent areasof the sheet. comparatively heavy rolling stress, suflicient to elongatethe sheet substantially, is applied to at least two continuous,laterally spaced, longitudinal areas of the sheet limiting a centralarea between them. Not more than sufiicient rolling stress to causesubstantially less elongation of the sheet is applied simultaneously tothe central area. Elongation of the heavily stressed areas issufliciently greater than that of the central area that the central areaof the sheet is stretched substantially.

A series of transverse slits may be cut in the central area of the sheetprior to or during the rolling step, if desired, or the unslit sheet maybe rolled. When the sheet is slit, stretching the central area byelongation of the laterally spaced, heavily stressed areas during therolling step widens the slits to fonm openings of oval to substantiallyrectangular shape. When the sheet is unslit,

3,293,725 Patented Dec. 27, 1966 elongation of the heavily stressed,laterally spaced areas results in stretching and tearing the sheet in aseries of locations in the central area. Further stretching the centralarea of the sheet widens the transversely torn openings into crescentshape.

The final shape of the openings through the sheet is controlled by aselected differential in rolling stress applied to the heavily stressed,laterally spaced areas and the central area between them. Maximumdifierential in rolling stress and maximum width of the openings areobtained when no rolling stress is applied to the central area, and thewidth of the openings becomes correspondingly narrower as the degree ofstress applied to the central area increases. It will readily be seenthat, if rolling stress sufiicient to elongate the sheet in the centralarea be applied thereto, the stretching of the central area due toelongation of the heavily stressed areas will be decreased; and as thestretching efifect is decreased, the openings will be widened to alesser degree. Increase in rolling stress applied to the central areaalso results in wider spacing of torn openings in the central area dueto a lesser difierential in elongation between the central area and theheavily stressed areas.

The present process thus results in the formation of series of openingsof desired shape in a sheet of malleable material by a simple rollingprocess. The degree of rolling stress is controlled to form openings ofa desired size and shape. Control of rolling stress preferably iscarried out by use of a machine having rolls which are adjustable towardand away from each other and constructed to apply greater rolling stressto the laterally spaced, longitudinal areas than to the central areabetween them.

No specific differentials in rolling stress can be stated since thisdifferential will vary according to the characteristics of theparticular malleable material being rolled and to the shape of openingsdesired in a sheet of this material. The degree of stress to be appliedwill be known approximately to those skilled in the art of rollingmetal, and preferably the rolls are set at a distance to each other togive approximately the elongation required. The sheet of metal is thenintroduced between the rolls and pressure is adjusted to give openingsof the desired shape. Each different batch of sheet material rolled mayrequire a somewhat different adjustment, and the pressure is controlledthroughout the rolling step to give openings of desired shape.

The machine of the present invention is a very simpleone. It includes atleast one pair of power-driven opposed rolls. At least one roll of thepair has laterally spaced shoulders thereon opposed to a cylindricalsurface on the other roll. Each pair of shoulders defines a groovebetween them which extends circumferentially around the correspondingroll. This arrangement enables the application of heavy rolling stressto a sheet of material at locations where the sheet passes between theshoulders and the opposite roll while the circum-- ferential groovesprovide a differential in rolling stress applied to a central areabetween the shoulders and rolling stress exerted by the shoulders. Thedepth of the groove or, stated conversely, the height of the shoulders,is selected to give a selected dilferential in rollingstress applied tothe laterally spaced areas of a sheet passing between the shoulders andthe opposite roll and to the central area of the sheet passing betweenthe groove and the opposite roll. This differential may result fromapplication of no rolling stress at all in the area between the grooveand the opposite roll, up to a degree of rolling stress suflicient toelongate the sheet substantially in this area, but with less elongationthan in those areas of the sheet passing between the shoulders and theopposite roll. Alternatively, the groove may be filled or partiallyfilled with an elastic, compressible material of hardness selected toapply a selected degree of rolling stress to the central area of thesheet.

Means for driving the pair of rolls is provided, and a means for movingat least one of the rolls toward and away from the opposite roll isincluded.

The invention may be best understood on reference to the followingdetailed description and the attached drawings wherein like referencecharacters are used throughout to designate like parts and:

FIG. 1 is an elevation, partially in section, of one preferred devicefor applying a differential in rolling stress to adjacent areas of asheet;

FIG. 2 illustrates a modification of the rolls of the device of FIG. 1;

FIG. 3 illustrates another modification of the rolls;

FIG. 4 illustrates one arrangement of slitting roll and backing rolladapted to slit a sheet of malleable material passed between the rollstransversely;

FIG. 5 illustrates a sheet of malleable material having transverse slitsadapted to be expanded by application of differential rolling stress toadjacent longitudinal areas of the sheet;

FIG. 6 illustrates two sheets similar to the sheet shown in FIG. 5 afterapplication of a differential in rolling stress to adjacent longitudinalareas of the sheet; v FIG. 7 illustrates an unslit sheet which may betreated by the process of this invention; and

FIG. 8 shows two sheets having crescent openings torn transverselytherein and expanded to various widths by selected differentials inrolling stress applied to sheets similar to those shown in FIG. 7.

The device of FIG. 1 comprises a base 1 and supporting members 2 and 3mounted thereon. A pair of cylindrical, opposed rolls, designatedgenerally as 4 and 5, are mounted upon axles 6 and 7 carried in bearings8 and 9 disposed in supporting members 2 and 3. The bearings 9 areillustrated as in fixed positions in supporting members 2 and 3.

Shaft 6 is journaled in bearings 8 which are movable toward and awayfrom bearings 9 so shaft 6, bearings 8, screw 10 and wheel 11 cooperateto form a means for moving roll 4 toward and away from roll 5 and thusto adjust pressure on a sheet of malleable material passing betweenrolls 4 and 5. A means for driving the pair of rolls, illustrated asmotor 12 attached to shaft 7, is provided.

The roll 4 includes shoulders 13, 14 and 15 which have cylindricalsurfaces opposed to a cylindrical surface of roll 5. Shoulders 13 and 14define a groove 16 between them while a second groove 17 is definedbetween shoulders 14 and 15. Grooves 16 and 17 are filled with anelastic compressible material 18.

The modified pair of rolls shown in FIGS. 2 and 3 may be substituted forrolls 4 and 5 if desired. Roll 4a of FIG. 2 differs from roll 40f FIG. 1only in the omission of the elastic compressible material 18 fromgrooves 16a and 17a, respectively, defined by shoulders 13a and 14a andshoulders 14a and 15a. Rolls of the type shown in FIG. 2 are preferredwhen maximum differential in rolling stress is to be applied.

The rolls shown in FIG. 3 are each identical to roll 4' of FIG. 1 andare arranged so shoulders 13, 14 and 15 run upon corresponding shoulders13b, 14b and 15b of roll 55. Each of the circumferential grooves aroundthe corresponding roll defined between shoulders 13 and 14 and betweenshoulders 14 and 15 and between the corresponding shoulders on roll 5bare illustrated as filled with the compressible elastic material 18although it is to be understood the elastomer may be omitted from one orboth rolls if desired.

In operation when it is desired to produce a sheet having a series ofopenings of oval to' substantially rectangular shape, a sheet 20 ofmalleable material may be passed between a slitting roll 21 equippedwith a series of knives 22 adapted to slit the sheet, and a backing roll23 as shown in cross section in FIG. 4. The resulting slit sheet willthen have the appearance illustrated as 20a in FIG. 5. Alternatively,the roll 4a may be equipped with slitting knives longitudinally disposedin slits 16a and 17a and the slitting may be performed during therolling operation.

The slitting operation results in initially parting the sheettransversely in a series of locations in longitudinal central areaslimited by unslit areas of the sheet. The sheet 20a shown in FIG. 5 isin reduced scale and is of such width that unslit longitudinal areas ofthe strips 24, 25 and 26 substantially correspond in Width to the widthof shoulders 13, 14 and 15 on roll 4, while the length of slits 27 doesnot exceed the width of grooves 16 and 17. The sheet is started betweenthe pair of rolls 4 and 5, and pressure between the rolls is adjusted byadjustment of wheels 11 and screws 10 moving the pair of bearings 8carrying shaft 6 and roll 4 toward or away from roll 5 to secure thedesired degree of elongation of the longitudinal areas 24, 25 and 26 ofthe sheet.

The differential in rolling stress applied to the longitudinal slit areaon sheet 20a and the longitudinal areas 24, 25 and 26 will result inelongation of the slit area by stretching and in opening the slits. Whensubstantially no rolling stress is applied to the transversely slit area28', as will be the case when a roll such as 4a of FIG. 2 is used, theslits will be expanded to maximum width as illustrated in FIG. 6A. Whena greater degree of rolling stress is applied to area 28, as by use ofrolls arranged as shown in FIG. 1, the slits will be opened to a lesserdegree as shown at B in FIG. 6 to have the final configuration shown at27b. In order to obtain the narrower configuration, the slit area hassufficient stress applied that there is some elongation of area 28 butnot so much. as in the rolled areas 24b, 25b and 26b of FIG. 6.

The degree of rolling stress to be applied is pre-selected by selectinga material 18 of hardness suitable for the sheet to be rolled. Thehardness of elastic compressible materials on the market is well knownas is the degree of malleability of various materials to be rolled.Thus, the operator may select from available materials suitablecompressible materials to fill the slots 16 and 17.

When a plain sheet, such as that designated as 29 in FIG. 7, is to berolled, rolls arranged as shown in FIG. 2 result in tearing the striptransversely in central areas 33 and 34 located between adjoininglongitudinal, heavily stressed areas 30, 31 and 32. The strip is torntransversely when no rolling stress or very light rolling stress isapplied to areas 33 and 34, and the resulting openings have crescentshape and maximum breadth as indicated in a r-olled strip designatedgenerally as C in FIG. 8.

Application of increased rolling stress to areas 33 and 34 results inthe formation of crescent-shaped openings which are torn in the centralareas by the expansion of areas 30, 31 and 32, but the resultingcrescent openings are narrower than those which are formed whensubstantially no rolling stress is applied. The spacing of openingsunder these conditions also is somewhat wider than when little rollingstress is applied since the difierential in elongation between thecentral area and the heavily stressed areas is smaller. It will thus beseen that the shape and longitudinal spacing of openings in a rolledstrip may be controlled by controlling the degree of rolling stressapplied.

In this specification and claims, the term sheet of malleable materialis used to include materials of various weights, such as thosecommercially sold under the designation of strip, sheet and light platematerials. The maximum weight or thickness of a sheet to be handled bythis process will depend upon the malleability of the material and notupon the commercial designation.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the process and apparatus.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. In a process of manufacturing a sheet of malleable material having aseries of openings therethrough, the step of applying rolling stress tolaterally spaced apart longitudinal areas of the sheet 'which issufiiciently greater than that simultaneously applied to an unslitlongitudinal area therebetween that the elongation of the laterallyspaced apart areas relative to the unslit area will stretch said unslitarea to cause it to tear at longitudinally spaced apart locationstherealong.

2. In a process of the character defined in claim 1, wherein arelatively light rolling stress is applied to said unslit area.

3. In a process of the character defined in claim 1, wherein no rollingstress is applied to said unslit area.

4. In a process of manufacturing a sheet of malleable material having aseries of openings therethrough, the steps of advancing the sheet havingan unslit longitudinal area between a pair of rollers having at leastone pair of laterally spaced apart shoulders for applying rolling stressto laterally spaced apart longitudinal areas of said sheet on oppositesides of the unslit area and adjusting the rollers relative to oneanother in order to apply rolling stress to the laterally spaced apartareas of the sheet which is sufficiently greater than that applied tothe unslit area as to tear said unslit area at longitudinally spacedapart locations therealong.

5. A machine for forming openings in a sheet of malleable material,comprising a pair of opposed rollers, means for supporting the pair ofrollers in substantially parallel position, one of said rollers having apair of laterally spaced apart shoulders opposed to the other roller soas to provide a circumferential groove around the roller between theshoulders, said groove being substantially filled with an elasticcompressible material, and means for adjusting the rollers toward andaway from each other into cooperative position to apply selected rollingstresses to longitudinal areas of the sheet as it is advanced betweenthe rollers.

6. A machine of the character defined in claim 5, wherein the otherroller also has laterally spaced apart shoulders thereon opposed to theshoulders of the firstmentioned roller to provide a circumferentialgroove therebetween opposed to the groove on said first-mentionedroller, said groove in the other roller also being substantially filledwith an elastic compressible material.

References Cited by the Examiner UNITED STATES PATENTS 1,696,833 12/1928Bates 296.1

RICHARD H. EANES, JR., Primary Examiner.

1. A IN A PROCESS OF MANUFACTURING A SHEET OF MALLEABLE MATERIAL HAVINGA SERIES OF OPENINGS THERETHROUGH, THE STEP OF APPLYING ROLLING STRESSTO LATERALLY SPACED APART LONGITUDINAL AREAS OF THE SHEET WHICH ISSUFFICIENTLY GREATER THAN THE SIMULTANEOUSLY APPLIED TO AN UNSLITLONGITUDINAL AREA THEREBETWEEN THAT THE ELONGATION OF THE LATERALLYSPACED APART AREAS RELATIVE TO THE UNSLIT AREA WILL STRETCH